feat(storage): 实现本地存储功能，包括文件上传和下载接口

backend/providers/storage/config.go

@@ -0,0 +1,8 @@
+package storage
+
+type Config struct {
+	Type      string `json:"type" yaml:"type" toml:"type"`                   // local, s3
+	LocalPath string `json:"local_path" yaml:"local_path" toml:"local_path"` // for local
+	Secret    string `json:"secret" yaml:"secret" toml:"secret"`             // for signing
+	BaseURL   string `json:"base_url" yaml:"base_url" toml:"base_url"`       // public url prefix
+}

backend/providers/storage/provider.go

@@ -0,0 +1,74 @@
+package storage
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"net/url"
+	"strconv"
+	"time"
+
+	"go.ipao.vip/atom/container"
+	"go.ipao.vip/atom/opt"
+)
+
+func Provide(opts ...opt.Option) error {
+	o := opt.New(opts...)
+	var config Config
+	if err := o.UnmarshalConfig(&config); err != nil {
+		return err
+	}
+	return container.Container.Provide(func() (*Storage, error) {
+		return &Storage{Config: &config}, nil
+	}, o.DiOptions()...)
+}
+
+type Storage struct {
+	Config *Config
+}
+
+func (s *Storage) SignURL(method, key string, expires time.Duration) (string, error) {
+	exp := time.Now().Add(expires).Unix()
+	sign := s.signature(method, key, exp)
+
+	baseURL := s.Config.BaseURL
+	// Ensure BaseURL doesn't end with slash if we add one
+	// Simplified: assume standard /v1/storage prefix in BaseURL or append it
+	// We'll append /<key>
+
+	u, err := url.Parse(baseURL + "/" + key)
+	if err != nil {
+		return "", err
+	}
+
+	q := u.Query()
+	q.Set("expires", strconv.FormatInt(exp, 10))
+	q.Set("sign", sign)
+	u.RawQuery = q.Encode()
+
+	return u.String(), nil
+}
+
+func (s *Storage) Verify(method, key, expStr, sign string) error {
+	exp, err := strconv.ParseInt(expStr, 10, 64)
+	if err != nil {
+		return fmt.Errorf("invalid expiry")
+	}
+	if time.Now().Unix() > exp {
+		return fmt.Errorf("expired")
+	}
+
+	expected := s.signature(method, key, exp)
+	if !hmac.Equal([]byte(expected), []byte(sign)) {
+		return fmt.Errorf("invalid signature")
+	}
+	return nil
+}
+
+func (s *Storage) signature(method, key string, exp int64) string {
+	str := fmt.Sprintf("%s\n%s\n%d", method, key, exp)
+	h := hmac.New(sha256.New, []byte(s.Config.Secret))
+	h.Write([]byte(str))
+	return hex.EncodeToString(h.Sum(nil))
+}